import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char[] s= in.next().toCharArray();
        int n=s.length;
        StringBuffer ret = new StringBuffer();
        for(int i=0;i<n;i++){
            if(ret.length()==0||s[i]!=ret.charAt(ret.length()-1)){
                ret.append(s[i]);
            }else{
                ret.deleteCharAt(ret.length()-1);
            }   
        }
        System.out.println(ret.length()==0?0:ret);
    }
}